Liquid developing devices are known in which an electrostatic latent image is developed using a liquid developing agent. One conventional example discloses a liquid developing device in which a corona charger is disposed upstream of a developing area where a developing roller (developing agent holder or developer carrier) contacts a photosensitive drum. The corona charger charges a liquid developing agent held on the developing roller with a bias voltage having the same polarity as toner particles in the liquid developing agent, thereby compacting (or forcing) the toner particles toward the surface of the developing roller. Accordingly, toner particles transferred to a non-imaging area of an electrostatic latent image are reduced, preventing fogging in a developed image.
The above example also includes a cleaning member provided in the liquid developing device. The cleaning member contacts a surface of the developing roller to remove the excess liquid developing agent remaining on the developing roller after the development of an image.
However, in the liquid developing device having the above-described corona charger, toner particles forced from a surface layer of the liquid developing agent held on the developing roller into a deeper layer of the agent might be compacted in the deep layer. The deeper layer may refer to toner that is closer to the surface of the developing roller, while a surface layer of the toner may exist further away from the surface of the developing roller. In this case, the compacted toner particles may be more difficult to remove, and the developing roller might not be cleaned effectively by the above-described cleaning member alone.
Compacted toner particles could be removed by pressing the cleaning member against the developing roller with an increased contact pressure. In this case, however, the cleaning member might damage the surface of the developing roller.